Broadband High Gain and Low Cross-Polarization Double Cavity-Backed Stacked Microstrip Antenna

This communication presents a novel stacked multi-resonator two-layered suspended rectangular microstrip antenna (MSA) backed by double-cavity, which yields a wide bandwidth (BW) of 64% at the center frequency of 2.6 GHz, due to additional resonances introduced by the cavity. The proposed antenna has high radiation efficiency above 89.5% throughout the band yielding a maximum gain of 14.7 dBi and an average gain of 12.5 dBi. It has a stable radiation pattern and low cross-polarization better than -45 dB and yields uniform isolation better than 40 dB between two such antennas. Compared to without cavity-backed configuration, the proposed double cavity-backed configuration yields 82% more BW, 1.8 dB more gain, and 10 dB more isolation between the antennas. Simulated results are validated by measurements with a close agreement. Improved characteristics of the proposed antenna make it suitable for several applications including through the wall and ground penetrating radars (GPR).